Roll system for tensioning elongated work pieces

ABSTRACT

A roll system for tensioning elongated workpieces such as metal bands or webs of other material, wire and the like, comprises a pair of roll supports or stands, each provided with a plurality of rolls in mirror-symmetrical relationship with the rolls of the other stand. The mirror-symmetrical rolls are interconnected by a differential transmission, e.g. a planetary gear arrangement which is coupled with a respective hydraulic motor receiving fluid from a variable-capacity hydraulic pump common to all of the motors for establishing the necessary torque at the rolls.

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[ 1 Mar. 27, 1973 Waited States Patent 91 [54] ROLL SYSTEM FOR TENSIONING ELONGATED WORK PIECES am n m .mm mm n MD 6 6 9 1 4 [75] Inventor: Oskar Noe, Mulheim/Ruhr, Germany [73] Assigneei Fa. BWG Bergwe rk-und Walzwerk- 'f' Exami"er"Anen Knowles Assistant Examiner-Gene A. Church Alt0rney-Karl F. Ross Maschinebau G.m.b.II., Duisburg, Germany May 3, 1971 Appl. No.: 139,575

[57] ABSTRACT A roll system for tensioning elongated workpieces such as metal bands or webs of other material, wire and the like, comprises a pair of roll supports or [22] Filed:

stands, each provided with a plurality of rolls in mir- [Sl] Int. Cl. 23/08 42, 38, 39, 40,

rot-symmetrical relationship with the rolls of the other [58] Field of Search..'......226/195, 31

stand. The mirror-symmetrical rolls' are intercon- 226/111 183 nected by a differential transmission, e.g. a planetary gear arrangement which is coupled with a respective hydraulic motor receiving fluid from a variable- References Cited UNITED STATES PATENTS capacity hydraulic pump common to all of the motors for establishing the necessary torque at the rolls.

8 Claims, 4 Drawing Figures Lewis et al.

PATENTEUHARZYISYS SHEET 10F 2 INVENTORI Oskar Noe a 04m Attorney PATENTEUmzma SHEET 2 OF 2 INVENTORZ Oskar No ROLL SYSTEM FOR TENSIONING ELONGATED WORK PIECES FIELD OF THE INVENTION My present invention relates to a roll system for advancing continuous or elongated workpieces, especially bands, strips, webs or wire of metal or other material, whereby a predetermined tension is applied to the workpiece between the roll stations. More par- BACKGROUND OF THE INVENTION The use of roll systems to advance or control the tension during advance of metal bands, textile webs, paper webs and like elongated (continuous) flexible workpieces along a predetermined transport path, is common in many industrial applications. Such roll systems may, for example, be used to straighten sheet metal strips, to hold a strip for processing and to stretch or tension the strip as part of a metal working process, e.g. to effect a grain or crystallographic re-orientation.

In prior art constructions of such systems, a pair of roll stations or stands are provided in spaced-apart relation and are spanned by the elongated workpiece which frictionally engages the peripheries of the rolls of these stations. Depending upon the material of the workpiece and the degree of elongation, stretch or tensile stress generated thereon, the rolls are subject to more or less considerable stress.

To provide the desired tension, the rolls may be operated, according to conventional techniques, at the same speed, providing that the roll diameters are adjusted to allow different peripheral speeds at contact with the elongated workpiece.

Alternatively, the downstream rolls may be rotated at higher angular velocities than the upstream rolls and hence with higher peripheral speeds. In general the tension will depend upon these relationships and the frictional contact between the workpiece and the rolls. To increase this frictional contact, it is common practice to provide two or more rolls in each stand or at each station, the workpiece passing around one roll and onto and around another.

Numerous. systems have been provided to couple the rolls in order to generate the desired degree of stretch or generate. a desired tension in the workpiece passing between the rolls. For example, all of the rolls of one station may be connected together for synchronous rotation and connected by differential gearing to the synchronously operating rolls of the other station, a motor being provided to drive the differential. Hydraulic motors may be provided for the rolls of the two stations and can be connected to a common source of hydraulic fluid in parallel. Electric motors may be provided for the rolls of the two stations.

In each of the aforedescribed systems,'however, difficulties have been encountered. For example, where the rolls of each station or stand are driven synchronously, the stress accompanying the application of stretch forces to the band, is applied unequally to the rolls. Systems which require larger diameterrolls at certain locations at each station, have the disadvantage that the rolls are not interchangeable and considerable care must be taken to insure proper relationship of the roll diameters; hence even the slightest wear causes problems, and even the care required to insure a proper relationship of the diameters is insufficient when workpieces of different thickness are to be processed in the system. In the hydraulic and electrical arrangements, high costs, high repair frequency and large down-times are characteristic. I also may mention that it has been proposed to provide between a common drive of the-rolls of the several stands, and the driven rolls thereof, friction clutches which must be adjusted with care and are prone to breakdown.

OBJECTS OFTHE INVENTION It is the principal object of the present invention to provide a roll system for the purposes described which will obviate the aforementioned disadvantages.

It is another object of the invention to provide a tension arrangement for the stretching or tensile stressing of elongated workpieces, which is free from the high repair frequency noted in earlier systems, can make use of rolls of a single dimension, is of relatively inexpensive and simple construction, can be adjusted easily to establish the desired relationships of speeds of rolls, and is able to distribute the loading more uniformly to the rolls of each stand.

It is still another object of my invention to provide a roll system for the tensile stressing of elongated workpieces, especially bands, strips, webs and wire of metal or textile materials, in which a torque-distribution angular-velocity relationship of the rolls can be established in a simple and effective manner, with apparatus free from the tendency to break down.

SUMMARY OF THE INVENTION These objects and others which will become apparent hereinafter, are attained, in accordance with the present invention in a roll system in which a number of synchronously disposed rolls of the two stands or stations are interconnected by differential transmissions and are connected by the latter to respective drive means which need only establish the requisite torques, but may be used, if desired, to advance the workpiece.

According to a principle feature of the invention, the roll system for displacing elongated flexible workpieces, and for applying predetermined tension or stretch thereto, comprises a pair of roll stations or stands spaced apart in the direction of advance of the workpiece and provided with respective roll sets journalled on supports of the station. Each roll set includes a plurality of rolls (i.e. at least two) with peripheries engageable with the workpiece and disposed in mirrorsymmetrical relationship with respect to the rolls of the other set. The mirror-symmetrical rolls of the two sets are each interconnected by a respective differential transmission which, moreover, couples each pair of mirror-symmetrical rolls to a respective drive motors.

According to another feature of the invention, the drive means, which is superimposed on the workpiecedisplacing drive, includes a respective controlledtorque motor drivingly connected to each of the transmissions and preferably of the hydraulic type. A source of hydraulic fluicl, such as a variable-displacement hydraulic pump, is connected in parallel to several hydraulic motors. Furthermore, each of the transmissions may include a pair of coaxial shafts respectively connected by a bevel gear arrangement with its roll and provided with sun gear and the planetary-gear carrier of a planetary-gear transmission. The ring gear of the latter may be connected to the motor.

According to another feature of the invention, the roll stands or stations include mutually proximal upper rolls, i.e. upper rolls which are closer to one another across the transport path than the lower rolls, and mutually distal lower rolls provided with the respective transmissions. In a variant, the upper rolls may be mutually distal while the lower rolls are mutually proximal.

The differential relationship between the rolls of the stands guarantees a precise distribution of tensile or stretch forces between the individual rolls. The system has a specially simple construction by comparison with earlier arrangements as discussed above, and a decreased repair frequency with increased useful life. This is especially the case when the superimposed differential transmission is provided with a torque of moment responsive or controllable drive motor.

The desired torque may thus be established at each pair of mirror-symmetrical rolls independently of the speed of the pair, so that the tension is also applied independently of speed. In fact, the load speed can be provided by a drive means, totally independent of the torque-generating hydraulic motors, which engages the workpiece outside of the installation previously described.

' The desired relationship of the speeds of the motors I can be established while the predetermined tension is maintained constant, the instantaneous speed being automatically self-adjusted to maintain the predetermined tension. The torque relationships are maintained within each station and between the stations so that any increase or decrease in speed will result in an automatic or self-induced compensation to maintain the tension between the stations and between the rolls of these stations.

DESCRIPTION OF THE DRAWING drive means.

SPECIFIC DESCRIPTION As shown in FIG. 2, the roll system according to the present invention may comprise a pair of roll stations or stands provided with respective supports 1, 2, shown diagrammatically. Upper rolls 4 and (mutually distal) are journalled in the supports 1 and 2, respectively, in

paired, mirror-symmetrical relationship. The stands 1- and 2 are also provided with paired mutually proximal lower rolls 3 and 6. With the band being advanced in the direction of arrow A, c.g. by the drive system discussed in connection with FIG. 1 or a drive engaging the downstream portion of the band at some remote location, a stretch 17 is fed to the first roll 3 and undershoots the latter to pass via a stretch 18 around roll 4. The main tension stretch 16 between the rolls 4 and 5 leads around the latter roll and via a stretch 19 around roll 6. The band has a stretch 20 leading from the roll installation.

A functionally similar system is shown in FIG. 3 wherein the stands 1' and 2 are provided with mutually proximal upper rolls 3, 6 and mutually distal lower rolls 4, 5 in mirror-symmetrical relationship. When the band is displaced in the direction of arrow A, the stretch 17' passes initially over roll 3' and then, via stretch 18' onto the roll 4'. The major portion of the band 16 bridges the roll stand and passes onto roll 5'. The band then proceeds via stretch 19 over roll 6' whence it emerges at 20.

In the embodiments of FIGS. 2 and 3, the rolls 3, 3' and 6, 6 are provided with respective bevel gear arrangements 7 and 8 which couple these rolls to coaxial shafts 7a, 8a connected to a planetary-gear differential 9. Similarly, the rolls 4, 4' and 5, 5' are interconnected by a planetary-gear transmission 13 whose coaxial shafts 11a and 12a are tied to bevel-gear arrangements 11 and 12, respectively.

Each of the transmissions is provided with a respective hydraulic drive motor 10 or 14 whose drive pinions 23 and 24 rotate the ring gears 21 and 22 of the planetai'y gear transmissions 9 and 13, respectively. The ring gears 21 and 22 mesh externally with the pinions 23 and 24 and internally with the planetary gears 21a and 22a and the planetary-gear carriers 21b, 22b, respectively. The planetary-gear carriers 21b, 22b are connected to the shafts 8a or 12a. Similarly, the shafts 7a and are connected to the sun gears 21c, 22c, which mesh with the planetary gears 22a. The differential operation ofthe planetary gearing is well known in the art and reference is made in this regard to Chapter 1 1, pages llff of Marks Mechanical Engineers Handbook, McGraw-I-Iill Book Co., New York, 1958.

The hydraulic motors 10, 14 may be of the axialpiston type described at pages l99ff of Fluid Power, US Government Printing Office, Washington, D.C. 1966, and are of the controllable-torque type. As FIG. 4 illustrates, the hydraulic motors l0 and 14 are connected to a common reversible variable-stroke pump l5, e.g. of the axial-.pistop type discussed on pp. 1 l9 1 12 of Fluid Power (op. cit).

As indicated, the pump 15 is provided with a control member which can be shifted to positively displace fluid or to drain fluid from the network to maintain the desired pressure within the circuit. Instead of a pressure-control pump,-I may make use of a constant-volume pump (see pp. 94 ff. of Fluid Power (op. cit.) together with a pressure-control valve (pp. 164 ff. of Fluid Power op. cit.)

The hydromotors l0 and 14 establish the torque levels which are maintained between the rolls and the pairs of mirror-symmetrically disposed rolls. The motors operate only forwardly or rearwardly when a differential develops between the rolls, e.g.as a result of a non-uniform roll diameter, where the hand drive is external to the system as indicated at D in FIG. 2. Since the planetary gear transmissions establish a speed ratio between the sun gear and the planetary carrier (see Marks Mechanical Engineers Handbook, op. cit.), a corresponding ratio must be provided between the bevel gear arrangements 8 and 12, so that the speed ratio between the rolls is re-established at 1' i.

In operation the application may have various modes. For example, I may provide between the stations 1, 2 a stretch 16 to which a predetermined tensile stress is applied. Assuming that the band infeed stress at 17 is 2 tons (i.e. the retarding force on the band at 17 is 2 tons) the band passes around the roll 3 and then via stretch 18 onto roll 4. Between the rolls 3 and 4, I may raise the tension in stretch 18 to 6 tons. The first roll 3, therefore, must generate a tension of 4 tons in the band. If, in the stretch 16 between rolls 4 and 5, it is desired to bring the tension to 18 tons, these rolls must generate a torque corresponding to 12 tons. Furthermore, if it is desired to'reduce the tension in the stretch 19 between rolls 5 and 6 to 6 tons, the band may be led out at 20 with a tensile stress of 2 tons. In this embodiment, the torque of the transmissions 13 and 9 must be maintained in a ratio of l a 3. When the transmissions are provided with the necessary gear ratios to establish the torque increase, the hydromotors can be operated .with a common pressure line and the actual stress controlled by the hydraulic pressure. Each roll thus receives the appropriate torque while being rotatable relative to all the others at the necessary velocity. In practice, the rolls are all synchronized with one another by the band or wire workpiece which frictio nally connects them. I

When the system is used to straddle a metalworking or other machine,.an increase in length of the band may occur and the downstream rolls map rotate faster than the upstream rolls. Even in this case, the tension is maintained constant. The basic drive may be provided by the metal working machine or, as shown atD, via

the band-takeup drive.

In FIG. 3, l have shown a system in which the band is under a minimum stress or is even under zero stress. In other works, the tensile stress is maintained constant, but ata level approximately equal to zero. The rolls 3', 6' and 4', 5', in this case, reduce the tension at torque stretch 16' so that, if required, it is tensionless (the converse of FIG. 2). This is desirable where an intermediate processing in a bath, furnace or the like is-provided orwhere measurements, tests or the like must be made upon the workpiece' Various modifications will also be apparent within the scope of the claimed invention. For example, three, four or more rolls may be provided at each stand, the system may be used for other workpieces, etc.

I claim:

1. A roll system for tensioning an elongated flexible workpiece, comprising:

a pair of roll stations spaced apart in a direction of advance of said workpiece;

a respective roll set, each including at least two rolls with peripheries engageable with said workpiece, journaled at each of said stations and disposed mirror-symmetrically with respect to the rolls of the other set;

drive means for advancing said workpiece in said direction and thereby rotating said rolls;

a respective differential transmission rotatably interconnecting the mirror-symmetrical rolls of said sets; 1

a respective controlled-torque hydraulic drive motor operatively connected to each of said transmissions; and

a variablepressure source of hydraulic fluid including a variable-output hydraulic pump connected in parallel to said motors, each of said transmissions including:

a respective shaft connected to a roll of each set,

the shafts of each transmission being coaxial;

a sun gear connected to one of said shafts;

a planetary-gear carrier connected to the other of said shafts; 1

planetary gears journaled on said carrier and meshing with said sun gear; and

a ring gear meshing with said planetary gears and connected with the respective hydraulic motor, each of said stations being provided with a roll support, the rolls of said sets being journaled at said supports, said sets including mutually distal upper rolls and mutually proximal lower rolls in mirror-symmetrical relationship, said workpiece passing initially over the lowerroll of one of said sets and thereafter around the upper roll of said one of said sets, the upper roll of the other of said sets and the .lower roll of said other set.

2. The roll system defined in claim 1 wherein each of said shafts is drivingly connected to the respective roll by a bevel-gear arrangement.

3. A roll system for tensioning an elongated flexible workpiece, comprising:

a pair of roll stations spaced apart in a direction of advance of said workpiece;

a respective roll set, each including at least two rolls with peripheries engageable with said workpiece, journaled at each of said stations and disposed mirror-symmetrically with respect to the rolls of the other set;

drive means for advancing said workpiece in said direction and thereby rotating said rolls;

a respective differential transmission rotatably interconnecting the mirror-symmetrical rolls of said sets;

a respective controlled-torque hydraulic drive motor operatively connected to each of said transmissions; and

a variable-pressure source of hydraulic fluid including a variable-output hydraulic pump connected in parallel to said motors, each of said transmissions including:

a respective shaft connected to a roll of each set,

the shafts of each transmission being coaxial;

a sun gear connected to one of said shafts;

a planetary-gear carrier connected to the other of said shafts;

planetary gears journaled on said carrier and meshing with said sun gear; and

a ring gear meshing with said planetary gears and connected with the respective hydraulic motor, said stations each being provided with a roll support, said rolls being journaled on said roll supports and including a set of mutually proximal upper rolls and a set of mutually distal lower rolls, each set being provided with a respective one of said transmissions, said workpiece passing initially over the upper roll of one of said sets and thereafter over the lower roll of said one of said sets, the lower roll of the other set and the upper roll of said other set.

4. The roll system defined in claim 3 wherein each of said shafts is drivinglyconnected to the respective roll by a bevel-gear arrangement.

5. A tensioning device for continuous strip comprising a pair of spaced apart roll stands each having at least a pair of rolls engaging the strip for tensioning said strip between said stands, said strip being slung around said rolls, the rolls of each stand being'in mirror-symmetrical arrangement with respect to the rolls of the other stand, and respective independent variable drive transmissions interconnecting the mirror-symmetrical rolls of said stands and independent of any means for advancing the strip. 7

6. The device defined in claim 5 wherein each of said transmissions includes a controllable-torque prime mover.

7. The device defined in claim 6 wherein each of said controllable-torque prime mover is a hydraulic motor, said device further comprising a pressure-control pump connected ih common to said motor.

8. The device defined in claim 7 wherein each of said transmissions includes a differential gear arrangement.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTEON Patent No. 776 Dated 27 r h 1973 Inventbfls) Oskar NOE I It is certified thgyt error appears in the above-identified patent and that said Letters Patent are hereby corrected as showri below:

After line [21] insert the following:

[30] Foreign Application Priority Data I a Mayliiriro GERMANY P 2o 22 380.7

Signed and sealed this 20th day of November 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. RENE D; TEGTMEYER Attesting Officer Acting Commissioner of Patents FORM PO-1050 (10-69) v uscoMM-Dc scan-ps 9 us. GOVERNMENT PRINTING OFFICE l95 o-ass-su, 

1. A roll system for tensioning an elongated flexible workpiece, comprising: a pair of roll stations spaced apart in a direction of advance of said workpiece; a respective roll set, each including at least two rolls with peripheries engageable with said workpiece, journaled at each of said stations and disposed mirror-symmetrically with respect to the rolls of the other set; drive means for advancing said workpiece in said direction and thereby rotating said rolls; a respective differential transmission rotatably interconnecting the mirror-symmetrical rolls of said sets; a respective controlled-torque hydraulic drive motor operatively connected to each of said transmissions; and a variable-pressure source of hydraulic fluid including a variable-output hydraulic pump connected in parallel to said motors, each of said transmissions including: a respective shaft connected to a roll of each set, the shafts of each transmission being coaxial; a sun gear connected to one of said shafts; a planetary-gear carrier connected to the other of said shafts; planetary gears journaled on said carrier and meshing with said sun gear; and a ring gear meshing with said planetary gears and connected with the respective hydraulic motor, each of said stations being provided with a roll support, the rolls of said sets being journaled at said supports, said sets including mutually distal upper rolls and mutually proximal lower rolls in mirror-symmetrical relationship, said workpiece passing initially over the lower roll of one of said sets and thereafter around the upper roll of said one of said sets, the upper roll of the other of said sets and the lower roll of said other set.
 2. The roll system defined in claim 1 wherein each of said shafts is drivingly connected to the respective roll by a bevel-gear arrangement.
 3. A roll system for tensioning an elongated flexible workpiece, comprising: a pair of roll stations spaced apart in a direction of advance of said workpiece; a respective roll set, each including at least two rolls with peripheries engageable with said workpiece, journaled at each of said stations and disposed mirror-symmetrically with respect to the rolls of the other set; drive means for advancing said workpiece in said direction and thereby rotating said rolls; a respective differential transmission rotatably interconnecting the mirror-symmetrical rolls of said sets; a respective controlled-torque hydraulic drive motor operatively connected to each of said transmisSions; and a variable-pressure source of hydraulic fluid including a variable-output hydraulic pump connected in parallel to said motors, each of said transmissions including: a respective shaft connected to a roll of each set, the shafts of each transmission being coaxial; a sun gear connected to one of said shafts; a planetary-gear carrier connected to the other of said shafts; planetary gears journaled on said carrier and meshing with said sun gear; and a ring gear meshing with said planetary gears and connected with the respective hydraulic motor, said stations each being provided with a roll support, said rolls being journaled on said roll supports and including a set of mutually proximal upper rolls and a set of mutually distal lower rolls, each set being provided with a respective one of said transmissions, said workpiece passing initially over the upper roll of one of said sets and thereafter over the lower roll of said one of said sets, the lower roll of the other set and the upper roll of said other set.
 4. The roll system defined in claim 3 wherein each of said shafts is drivingly connected to the respective roll by a bevel-gear arrangement.
 5. A tensioning device for continuous strip comprising a pair of spaced apart roll stands each having at least a pair of rolls engaging the strip for tensioning said strip between said stands, said strip being slung around said rolls, the rolls of each stand being in mirror-symmetrical arrangement with respect to the rolls of the other stand, and respective independent variable drive transmissions interconnecting the mirror-symmetrical rolls of said stands and independent of any means for advancing the strip.
 6. The device defined in claim 5 wherein each of said transmissions includes a controllable-torque prime mover.
 7. The device defined in claim 6 wherein each of said controllable-torque prime mover is a hydraulic motor, said device further comprising a pressure-control pump connected in common to said motor.
 8. The device defined in claim 7 wherein each of said transmissions includes a differential gear arrangement. 